Heretofore, there have been used various black ink compositions as writing ink, ink-jet printing ink and stamp ink, which are used for recording on materials to be recorded, such as paper, etc.
Solvent-based ink has an advantage that it dries quickly at the time of printing; the written ink hardly blurs; it is usable for be recording on a resin film; and written and recorded characters are comparatively fast. However, xylene-dissolved type solvent-based ink, and industrial solvent-based ink for ink-jet printing prepared by dispersing a pigment in a resin solution of a ketone solvent, have a problem of environmental pollution due to odor. Recently, there have been required solvent-based ink using alcoholic organic solvents such as ethyl alcohol, propylene glycol monomethyl ether, etc.
As the black dye which is superior in solubility in the alcoholic organic solvent, for example, an amine salt of azoic chrome complex salt dye, nigrosine dye and an organic acid salt thereof are known.
However, solvent-based ink using an alcohol-soluble chrome complex salt dye (e.g. C.I. SOLVENT BLACK 23, 27, 29) contains a heavy metal such as chrome, etc. and has a problem in view of safety and environmental pollution. Ink using an nigrosine basic dye also has poor storage stability.